Oiltight seal for flexible couplings



Patented Jan. 27, 1942 --2,271,oso OILTIGHT SEAL FOR FLEXIBLE courLmos Lynn B. Case, N

ew Brunswick, N. J., asignor to John -Waldron Corporation, New Brunswick, N. J., a corporation of New Jersey Application May 7, 1940, Serial No. 333,757

1 Claim.

This invention relates to flexible couplings and more especially to flexible couplings of the gear type. Such a coupling consists of two identical externally geared hubs keyed to the shafts to be coupled. The hubs are connected and enclosed by a two-piece internally geared floating cover sleeve. The two pieces of the sleeve are rigidly interconnected so as to function as a single unit. In compensating for shaft misalinement, the cover sleeve generally assumes a neutral position between the hubs.

Heretofore, attempts-have beenmade to pro vide an oil tight seal between'the hubs and the sleeve by means of aringe of resilient material interposed therebetween, the ring consisting largely of rubber. Such ring was set into a roove with the major portion thereof received within the groove and with just enough of the. ring projecting beyond the edge of the groove toestablish sealing contact. The'ring was in contact with the entire surface of the groove in such manner that the major portion of the ring was positively confined and no substantial change of shape of the ring cross section was possible. In the operation of the flexible coupling, such ring wassubjected to varying pressure conditions resulting from relative axial movement of the sleeve and hubs and the varying pressure applied. to the exposed surface of the ring resulted in alternate compression and expansion of the ring without any substantial change of cross-sectiona1 shape. The consequent change of density produced crystallization and fatigue, thus destraying the effectivenesss of the ring as a seal after a comparatively short life.

An object of this invention is the provision in a gear type coupling of a resilient sealing ring capable of change. of cross-section when subjected to change of pressure, thereby avoiding change of density under varying pressure conditions with the result that the ring retains its resiliency and its high efficiency indefinitely.

According to this invention, the resilient ring is arranged in a groove and'either the crosssectional contour of the groove or the cross-sectional contour of the .ring is such that when the ring is subjected to pressure variations there is a resulting change of cross-sectional shape without substantial change in the density. With this arrangement, advantage is taken of the characteristic of rubber that its resiliency #Tncreased by repeated changes of applied press e? providing the rubber is free to change shape without substantial variation in density. Crystallization and fatigue of the rubber are thus avoided and Fig. 2 is a fragmentary enlarged view similar I to Fig. 1, and

Figs. '3 and 4 are similar views illustrating modifications of the seal.

The coupling is of standar consists of two identical hubs it equipped with external gears II in combination with a sleeve composed of two identical sections I2 held together as a single rigid unit by-bolts I3. Each th an internal gear sleeve section is provided wi with the teeth of a H, the teeth of which mesh gear H in the usual manner; 'Sultable lubricant is provided in the sleeve to provide a irictlonally reducing film between the gear teeth. Sum lent clearance is provided betweenthe sleeve sect ons and the hubs to permit the necessary relative movement for proper operation of the coupling. Such clearance provides a passageway for the escape of oil from the cover sleeve during operation of the coupling. To prevent such escapeof lubricant, a'seal is provided between each cover section and each hub.

Referring now more especially to Fig. 2, an

annular straight-wall groove 15 is provided'in' each cover section II and in the groove is arranged a ring l6 of resilient material,- .The overall section of the ring 16 is substantially the same as the cross-section of the groove l5. except that the inner edgeof the ring "projects beyond the inner edge of the groovesufliciently. to

contact with the outer'surface of the hub Ill and the inner portion ofthe ring is of slightly less width than the width 01' the'groove. As shown in Fig. 2, the ring I6 is provided with annular cut-outs at H, such cut-outs lying below the inner edge of the groove l5 and from the inner. periphery of the cut-outs, the ring I8 is p! less width than the groove. When this ring is sub jected to increased compression due to relative movement of the hub and cover, the material of the ring is not unduly compressed, but instead extends in'w the cut-out'portions and the head portion 16a is free to tilt about some point in the body of the ring as a fulcrum. The rin l6, therefore, retains its elasticity indefinitely 5 and as long as it retains its elasticity, the ring d construction and I provides an oil tight seal between the cover sleeve and hub.

In the modification illustrated in Fig. 3, annular channels 88 are provided in the side walls of the groove I1 and the ring as has continuous side walls. With this arrangement, the application of a compression force to the inner face of the ring results in expansion of the ring i9 into the grooves 58, thereby preventing undue compression of the ring.

Fig. 4 illustrates a modification in which a roove 2?} is provided in the hub ill instead of a groove in the sleeve i2.- A ring 2! of resilient material is mounted in this groove for co-operation with the sleeve to form an oil tight seal. The groove and ring combination is shown with an annular cut-out 22 in the ring and with straight side groove walls similar to the modiiication of Fig. 2. However, in place of such arrangement, the groove and ring arrangement may be similar to that illustrated in Fig. 3.

In flexible couplings of the gear type to which this invention relates, the coupler housing transmits the torque from one shaft to the other without rotational resiliency and without rotary movement of either shaft relative to the housing'. The flexibility of the coupling is achieved through tipping of the axis of the housing relative to the axes of the shafts in cases when the shafts are not in true axial alignment. This tipping of the housing necessitates flexing of the portion of the gasket ring is, or 2 i, intermediate the face thereof which is seated in the base of the groove, and the opposite face which is in tight contact with the opposing circular face of the hub III (as shown in Figs. 2 and 3) or of the cover section I? (as shown in Fig. 4). Since there is no rotary movement of either shaft relative to the housing there is no rotary movement or slippage of either face of the gasket relative to the circular face of the shaft or housing with which it is contact. Such contact accordingly consti-.

tutesa dry oil-tight seal. No such dry, oil-tight seal is possible in devices wherein the gasket is required to slip or rotate relative to one of the faces with which it is in contact, for in such structures an oil film is necessary between the moving faces and the oil film permits passage or leakage of oil from the interior of the housing which is prevented by the present invention.

It is of course understood that various modifications may be made in'the structure above described, without in any way departing from the spirit of the invention as defined in the appends ed claim.

I claim:

In a gear-type flexible coupling comprising a driving shaft, a driven shaft in substantial axial aligmnent with said driivng shaft anda coupler housing transmitting torque from one shaft to another, said housing and shafts having opposed circular faces and one of said faces having a groove, a resilient gasket in said groove, said gasket having a portion provided with parallel side walls snugly fitting the side walls of the groove at the bottom thereof and normally immovable thereon, said gasket having another portion out of contact with the side walls of the groove and having parallel side walls and a surface in oiltight contact with the circular face opposite said groove and immovable thereon in normal operation of the coupling, and said gasket and the side walls of said groove having annular recesses between them intermediate said first and second named portions of the gasket, whereby the intermediate portion of the gasket is unrestrained but enclosed in said groove and whereby the gasket is capable of change of cross section within said groove when subjected to change of pressure.

. LYNN B. CASE. 

